FIG. 5.

Effect of DNA vaccinations on IFN-γ and IL-4 release. Splenocytes harvested on the seventh day after the third immunization were stimulated in vitro, with chemically-killed A/Chicken/Henan/12/2004 (H5N1) virus, A/Chicken/Jiangsu/7/2002 (H9N2) virus, with an irrelevant protein (BSA) as a negative control, or with ConA as a positive control. Cytokine ELISA detection kits were used to evaluate IFN-γ (A) and IL-4 (B) levels. The concentrations of the released cytokines (+standard deviation) were calculated using a cytokine standard curve on the same measuring plate (*p < 0.05 by Student's t-test compared to the BSA-stimulated value).